In June, there were two successive general Google June 2021 Spam Updates regarding the avoidance of spam pages in the search results and the integration of qualified outbound links on websites. Attempted manipulations of the ranking by link exchange programs, for example, are detected and penalized more effectively. You can read more about the Link-Tagging und Link-Spam Updates in the Google Search Central blog.
How Google uses AI to fight spam can be read here.
Also vividly described in the video “How Google keeps you save on Search“.